Imaging moves to new heights

‘Eye in the sky’ technology is becoming more affordable, but what is the most useful type of imaging and is it best to work with an experienced contractor or invest in your own technology? These are the issues to be discussed at the next meeting of the Agri-Tech East Remote Sensing and Monitoring Special Interest Group.

Satellite imagery is widely available but lacks the detail that can be gained by UAV (unmanned aerial vehicles), also known as drones.

James Foster-Clarke from Skyview Robotics explains that satellite imagery resolution is typically as low as 22 square metres per pixel which gives a grainy image and low definition. His company, which uses drones to fly low over the field, provides much greater information.

He says: “We able to provide images down to 1cm per pixel, giving a greater accuracy and more detailed information which can be gathered and analysed; for example, for weed and disease identification and to generate a biomass index.

“As the drones fly much closer to the canopy, the sensor can detect subtle differences in the canopy colour; this information is analysed using our own spectrometers. Using this research data we are building a database of plant histograms so that we can use the profiles to identify both weeds and diseases from the aerial images.

“This has resulted in the identification of blackgrass with 1cm resolution enabling farmers to record the populations and apply an accurate spraying programme to eradicate the weed.

“We can export our information into shape files, which are widely used by many software applications and also can be used by fertiliser spreaders, drills and sprayers, or alternatively into Google Earth.”

For some producers a bigger picture is required.

G’s Growers described, at the recent launch of the Eastern AgriGate Research Hub, how it was using imaging gained from using light manned planes. It is monitoring crop growth and developing detailed vegetation maps which provide improved intelligence when deciding field management strategy.

EmmaGarfield of G’s says: “The advantage of an aircraft is that you can gain more height enabling whole fields to be captured in one image.

“The spectral images show canopy coverage with dark green areas indicating vigorous growth and red where there is poor growth. We find that we are able to detect crop canopy variation in advance of visual ground-based monitoring or crop walking.

“When this map is compared with a soil map it is clear that the poorer growth correlates with soil of a different type. Armed with this information it is then possible to make crop management decisions at a sub field scale.

“For example, to apply more fertiliser or organic matter selectively to the areas of poorer soil, or indeed to reduce the use of inputs and grow a different crop on these areas that can be used to produce biomass for the anaerobic digester.”

Regular monitoring is recommended with a frequency determined by the crop type and if there are any inherent problems in the field, such as blackgrass. Every time data is gathered it adds more knowledge.

Working with a specialist allows access to their expertise and sophisticated imaging, however some farmers want to do the monitoring and imaging themselves.

To assist with this, Dr Dan MacLean, head of bioinformatics at The Sainsbury Laboratory on the Norwich Research Park, is investigating how hobby drones, bought off the shelf, could be fitted with an appropriate high-resolution sensor to make it affordable for farmers to monitor their crops more regularly where there is a high disease or pest risk.

However, as drones become more popular, both for commercial purposes and aircraft hobbyists, the Civil Aviation Authority (CAA) has implemented rules and restrictions. To help navigate the legal ramifications, Peter Lee, a senior associate with law firm Taylor Vinters LLP and one of Europe’s leading unmanned system lawyers, will be answering questions at the meeting about current UK legislation.

The meeting ‘Sensing in the Air’ is being held by the Agri-Tech East Remote Sensing and Monitoring Special Interest Group at Centrum, Norwich Research Park, Norfolk, NR4 7UG from 9.30am on the 1st December, 2015.